OSHA comments from the January 19, 1989 Final Rule on Air Contaminants Project extracted from 54FR2332 et. seq. This rule was remanded by the U.S. Circuit Court of Appeals and the limits are not currently in force.

CAS: 115-90-2; Chemical Formula: C11H17O4PS2

Previously, OSHA had no limit for fensulfothion. The ACGIH has a TLV-TWA of 0.1 mg/m3. The proposed PEL was 0.1 mg/m3 as an 8-hour TWA; NIOSH (Ex. 8-47, Table N1) concurs, and this limit is established by the final rule. Fensulfothion is a brown liquid at room temperature.

Fensulfothion has an acute oral LD(50) of 4 mg/kg in male rats and 1.8 mg/kg in female rats. Aerosol inhalation studies in rats have shown LC(50)s of 113 mg/m3 for a one-hour exposure and 29.5 mg/m3 for a four-hour exposure (Loeser and Kimmerle 1971, as cited in ACGIH 1986/Ex. 1-3, p. 266). This insecticide has been shown to have effects similar to those of the other thiophosphates, which cause cholinesterase inhibition. Dermal toxicity is high, with LD(50) values ranging between 14 and 30 mg/kg for male rats and between 3.5 and 3.0 mg/kg for females (NIOSH 1974d, as cited in ACGIH 1986/Ex. 1-3, p. 266). Tests of mice and rabbits have shown no embryotoxic, reproductive, or mutagenic effects. The no-effect dietary level in subchronic feeding studies is reported to be 1 ppm in rats and 2 ppm in dogs. The no-effect level for cholinesterase inhibition is reported as 1 ppm in the diet for both dogs and cats (ACGIH 1986/Ex. 1-3, p. 266).

In humans, dermal studies have shown irritation without cholinesterase effects from two-hour, twice-daily applications of a 5-percent granular formulation to the forearms of three subjects. Systemic absorption through the lungs has been demonstrated after inhalation of fensulfothion aerosols (ACGIH 1986/Ex. 1-3, p. 266). No comments, other than NIOSH’s, were received on this substance.

In the final rule, OSHA is establishing a PEL of 0.1 mg/m3 TWA for this previously unregulated substance to reduce the significant risks of metabolic effects and skin irritation. The Agency concludes that this limit will substantially reduce these risks, and that skin irritation and cholinesterase inhibition are material impairments of health.

Page last reviewed: September 28, 2011